Electrical measuring instrument



Dec. 27, 1927. N 1,654,308

R. T. PIERCE ELECTRICAL MEASURING INSTRUMENT Filed May 12, 1923 ATTORNEY Patented Dec. 27, 1927.

-UITE DF STATE-S PATENT OFFICE.

RAYMOND T. PIERCE, OF EAST PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WEST- INGHOUSE ELECTRIC & MANUFACTURING COMPANY, ACORPORATION OF PENN- SYLVANIA.

ELECTRICAL MEASURING INSTRUMENT.

Application filed May 12, 1923. Serial No. 638,626.

My invention relates to electrical measuring instruments and particularly to alternating-current ammeter or volt-meter mechanisms.

One object of my invention is to provide a device of the above-indicated character that shall be simple and durable in construction,

vide an alternating-current instrument that-v shall be better balanced, that shall have smoother operating characteristics and that shall operate over a more uniform scale.

Another object of myinvention is to provide an amineter structurethat shall be very easy to assemble and that'shall not readily get out of order.

A further object of my invention is to provide an ammeter structure that shall be extremelycompact and neat in appearance.

In practicing my invention, I provide a stationary hollow coil, a shaft disposedin spaced parallel-planerelation thereto and an armature disc mounted eceentrically on the shaft to be attracted by uniform increments into the space encompassed by the coil.. The various details of construction combine to render the arrangement extremely effective in operation, to simplify the assembly, to provide a uniform scale movement and to economize to a marked degree in the production of a high-grade instrument.

Figure 1 of the accompanying a plan view of a portion of an embodying my invention.

Fig. 2 is a side'elevational view of theinstrument shown in Fig. 1. Y I

Fig. 8 is av detail plan view of a novel form of armature disk employed in my invention.

The device of my invention comprises, in general, a stationary coil 1, a shaft2, an armature disk 3, a bushing a balance-weight arm 5 and a balance weight 6. I

The coil 1, having conducting leadsS and 9, is preferably of substantially oval shape to provide an elongated narrow opening 10 therein. a

The shaft 2, having usual end bearing portions 11 and 12, is disposed in spaced parallel-plane relation to the coil 1 and is adapted to receive the disc 3 at a position opposite the opening 10 inthe coil l.

drawing is nstrument The disc 3 is preferably of uniform cirl cular shape, except for a notch 14 in the .periphery thereof, although it may be otherwise formed, and is provided with an opening 15 that is offset from the central axis thereof. 7

The bushing 4, that is preferably press fitted in position on the shaft 2 opposite the opening 10 in the coil 1, has cylindrical portions 16 and 1'7 of different diameter to provide a shoulder 18 against which the disk 8 rests, when the smaller diametered portion 1is in position in the opening 15 of the c is c.

The balance-weight arm 5 comprises a fiat vdiscoidal inner portion 19, having an. opening by which it also surrounds the smaller portion 16 of the bushing 4, and a radially projecting arm portion that is bent laterally through the notch 14. i

After the above described members have been assembled in the positions shown, the

upper end 21 of the bushing 4 is swaged over to securely hold the disk '3 and thebalanceweight arm 5 in position on the bushing 4. The arrangement by which the balanceweight arm 5 is swaged in position at its inner end and is positioned in the notch 14 provides an extremely simple and effective method of fixing the arm 5 in position relative to the disk 3.

In operation, the disk 3 being eccentrically mounted on the shaft 2, will'be drawn into the opening 10 by uniformly varying degrees in proportion to the current traversing the coil 1 in opposition to a usual spring (not shown) thatis connected to the shaft 2. The degree of eccentricity of the disk 3 relative to the shaft 2 is predetermined to cause the latter to run through substantially equal increments of angular movement in response to equal increases of current in the coil 1, thereby permitting the use of a more uniform scale and greatly improving the opera tion of the'instrum'ent.

While I have-shown and described a particular form of my invention, changes may be effected therein without departing from the spirit and scope thereof, asset forth in the appended claims.

I claim as my invention: s

1. In an electrical measuring instrument, the combination with a shaft, of an arma ,ture disk member mounted thereon, and a 3. In an electrical measuring instrument,

the combination with a shaft, of an armature disk mounted thereon and having 21 peripheral notch, and a balance-weight arm secured to said shaft and extending along a surface of the disk and laterally through said notch to prevent angular movement of the arm relative to the disk.

4. In an electrical measuring instrument, the combination with a shaft, of an armature disk mounted eccentrically thereon and having a peripheral notch at the end of the shortest distance from the shaft on the diameter of the disk through'the axis of the shaft, and a balanccqveight arm secured to said shaft and extending along a surface of the disk and laterally through said notch to prevent angular displacement of the arm relvative to, the disk.

5. In an electrical measuring instrument, the combination with a coil and a shaft, of an armature disk member having an opening therethro-ugh, a balance-weight arm having an opening registering with said disk opening and a portion extending laterally from the shaft, a bushing on the shaft hav ing portions of different diameters to provide a shoulder against which said members rest, the smaller portion ofthe bushing ex tending through said openings and being provided with means to hold the disk and ,the arm in position, and means cooperating between the arm and the disk at a position rem'ovcd'froi'n the shaft for preventing angular movement of the arm relative to the disk.

6. In an electrical measuring instrument, the combination with a coil and a shaft, of an armature disk member having an opening therethrough and a peripheral notch, a balance-weight arm having an opening registering with said disk opening and a portion extending laterally from the shaft and longitudinally through said notch, and means for holding the disk and the arm in position comprising a bushing on the shaft having portions of different diameters to provide a shoulder against which said members rest, the smaller portion of the bushing extending through said openings.

7'. In an electrical measuring instrument, the combination with a coil and a shaft, of an armature disk member having an opening therethrough offset from the center thereof and a peripheral notch at the end of the shorter distance from the opening on the diameter of the disk throughthe opening,

a balance-weight arm having an opening registering with said disk opening and'a portion extending therefrom alonga surface of the disk, through said notch and outwardly from the edge of the disk, a bushing on the shaft having portions of different diameters to provide a shoulder against which said members restthe smaller portion of the bushing extending through said openmgs and being swaged over to hold the disk and the arm 1n pos1t1on,and 'a balance-welght member on said outwardly-extending portion of the arm.

8. In an electrical'measuring instrument, the combination with a coil, of a plurality of members comprising a shaft and an armature disk of magnetizable material, said armature disk being carried by said shaft, having its weight non-uniformly disposed with respect to the axis, of said shaft and projecting into the space encompassed by said coil, an arm carried by one of said members, and a weight adjustable on said arm outwardly of the periphery ofsaid ar' mature disk, sald weight being disposed substantially in the plane of said disk andon the side of said shaft occupied by the diskportion of minor weight.

9. In an electrical measuring instrument, the combination with a coil, of a plurality of members comprising a shaft and an armature disk of magnetizable material, said armature disk being eccentrically mounted on said shaft, having its Weight-nonuniformly disposed with respect to the axis of said shaft and projecting into the space encompassedby said coil, and a counterbalancing weight carric-dby one of said members, said counter-balancing weight beingdisposed substantially in the plane of said disk and on the side of said shaft occupied by the the combination with a coil, of a plurality of members comprising a shaft and an arhit) mature disk of magnetizable material, said passing through the center of gravity of said armature disk being eccentrically mounted disk and counterbalancing weight substanon said shaft, having its weight non-unitially coinciding With the axis of said shaft. formly disposed with respect to the axis of In testimony whereof, I have hereunto said shaft and projecting into the space ensubscribed my name this 9th day of May,

compassed by said coil, and a c0unterba1anc- 1923.. I ing weight carried by one of said members substantially in the plane of said disk, a line RAYMOND T. PIERCE. 

